Medical/biological study (experimental study)

The effect of mobile phone electromagnetic fields on the alpha rhythm of human electroencephalogram med./bio.

By: Croft RJ, Hamblin DL, Spong J, Wood AW, McKenzie RJ, Stough C

Published in: Bioelectromagnetics 2008; 29 (1): 1-10

Aim of study (acc. to author)

The study was designed to provide a methodologically rigorous test of the hypothesis that mobile phone-exposure increases alpha wave power in the EEG, by employing similar methodologies to Curcio et al. (publication 12357 ), but with a substantially larger sample size.

Background/further details

120 subjects were tested in awake resting position.

Endpoint

effects on the neurological system: neural activity

Exposure

- mobile communications
- digital mobile phone
- GSM

Exposure	Parameters
Exposure 1: 895 MHz Modulation type: pulsed Exposure duration: continuous for 30 min	power: 2 W peak value power: 0.25 W mean SAR: 0.674 W/kg maximum (10 g) (high on the cheek bone, midway between the auricle and temple) SAR: 0.11 W/kg maximum (10 g) (in-line with the antenna, approx. over the temporal lobe)

General information

Participants attended two sessions one week apart with a double blind, counterbalanced (left vs. right hemisphere exposure, between subjects), crossover (sham vs. active) design.

Exposure 1

Main characteristics

Frequency	895 MHz
Type	electromagnetic field
Exposure duration	continuous for 30 min

Modulation

Modulation type	pulsed
Pulse width	576 µs
Duty cycle	12.5 %
Repetition frequency	217 Hz
Additional info	GSM without discontinuous transmission (DTX) and adaptive power control (APC) with frequencies of 16 and 217 Hz detected using a pick-up coil at the back of the handset [Andersen and Pedersen, 1997]

Exposure setup

Exposure source	cellular phone continuous transmission
Chamber	The participants were seated in a comfortable chair, 1.5 m in front of a computer monitor.
Setup	The phone was placed in a cradle over the EEG recording cap, over the right or left temporal region (each for half the subjects), comparable to normal use (in "touch" position according to FCC Guidelines, 2001).
Sham exposure	A sham exposure was conducted.
Additional info	The handset's audio circuitry was disabled, and padding was placed between the handset and its leather casing to avoid acoustic and thermal cues. The used type of EEG recording cap did not display any EMF pickup within the physiologically important range relevant to this study (0.5-45 Hz) [Wood et al., 2003].

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power	2 W	peak value	-	-	-
power	0.25 W	mean	-	-	-
SAR	0.674 W/kg	maximum	measured	10 g	high on the cheek bone, midway between the auricle and temple
SAR	0.11 W/kg	maximum	measured	10 g	in-line with the antenna, approx. over the temporal lobe

Measurement and calculation details

SAR measurements were conducted inside a Specific Anthropomorphic Mannequin (SAM) phantom using a precision robot Dosimetric Assessment System (DASY4) without the EEG recording apparatus in place. The effect of the EEG cap and leads on the SAR was investigated by measurement and computation and is reported elsewhere [Hamblin et al., 2007]. Both methods predicted a decrease in SAR values to the head of up to 20%.

Reference articles

Hamblin DL et al. (2007): EEG electrode caps can reduce SAR induced in the head by GSM900 mobile phones
Wood AW et al. (2003): The use of a 'phantom scalp' to assess the possible direct pickup of mobile phone handset emissions by electroencephalogram electrode leads
Andersen JB et al. (1997): The Technology of Mobile Telephone Systems Relevant for Risk Assessment

Exposed system:

human
partial body: head (left or right temporal region)

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: neural activity (EEG; resting alpha wave power)
EOG

Investigated system:

investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

before exposure
during exposure
after exposure

Main outcome of study (acc. to author)

The study has replicated previous data of mobile phone-related increases in resting alpha wave, and thus adds strength to the argument at which there are mobile phone-related bioeffects at the low levels that mobile phones operate.
Although the functional significance of this alpha wave change cannot be determined at present, it should be pointed out that alpha wave changes of the magnitude reported in this investigation have not been found to relate to health outcomes, either positive or negative.

Study character:

medical/biological study
experimental study
full/main study
double-blind study; crossover study

Study funded by

National Health and Medical Research Council (NHMRC), Australia

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